1. Field of the Invention
The present invention relates to an image forming apparatus capable of designating an area to be copied of an original and more particularly a copying apparatus capable of designating an image area to be copied of an original and copying only the designated image area on a copy sheet; that is, a copying apparatus capable of designating an area to be copied.
2. Related background art
Recently the copying apparatus incorporating various functions has been widely used.
One of the new functions of the copying apparatus is to copy the images of a plurality of originals. That is, a plurality of originals are copied on a single copy sheet. For instance, assume that there are two originals bearing different image patterns to be copied. Then, the image pattern of one original is first copied on one major surface of a copy sheet and then the image pattern of the other original is copied on the same major surface of the same copy sheet, whereby the two image patterns of two different originals are copied on the single copy sheet. Thus, the multiple copying operation is accomplished. Such multiple copying operation can be performed by a conventional copying apparatus. That is, with the conventional copying apparatus, it suffices to insert a copy sheet which has the image pattern of a first original and is discharged from a copying apparatus, into the copying apparatus again through a manual copy sheet insertion means or the like so that the image pattern of a second original is copied on the same copy sheet. Meanwhile, there has been designed and constructed a copying apparatus of the type in which when the multiple copying operation is selected by an operation panel, a copy sheet is automatically circulated through the copying apparatus so that predetermined image patterns of a plurality of originals can be copied on a single copy sheet as the originals are replaced one by one. In another conventional copying apparatus, when a plurality of originals(for instance, two originals) are placed upon the original stand of the copying apparatus, the desired image pattern areas of the originals are automatically copied on a single copy sheet even when the originals are replaced.
Another novel function of the copying apparatus is to produce a copy sheet bearing a color image. In such color copying apparatus of the type described, instead of a black color developing device, color (for, instance, red, green and so on) developing devices are used, whereby a color image can be copied. In some color copying apparatus, the black color developing device is replaced by color developing devices. However, in case of a recently developed copying apparatus, in addition to a black-color developing device, color developing devices are already incorporated so that when the color copying is selected by the operation panel, copy sheets bearing a color image are automatically reproduced.
When the above-described multiple-image copying apparatus is combined with the above-described color copying apparatus, thereby may be provided a novel copying apparatus having various functions. In this case, when both the multiple copying operation and the color copying operation are selected, a copy sheets bearing predetermined color images of a plurality of original can be automatically reproduced. When the mode of operation is suitably selected, a copy sheet bearing a black-color image of one original and the desired color image of the other original may be obtained.
A further novel function of the copying apparatus is to designate an area to be copied of an original (or to detect coordinate points) so that only an image in a preselected area of an original is copied. According to a conventional method to carry out such process as described above, a desired image area is selected or designated in terms of X and Y coordinates which are entered by an operation panel. Then, in response to the signals representative of the X and Y coordinates, an array of light-emitting elements disposed in the vicinity of a photosensitive member are partially and time-serially turned on so that an electrostatic image in an undesired area on the photosensitive member is erased, whereby only the desired image area is copied.
Recently, there has been proposed a method in which a desired image area is designated by coordinate position detection elements (so-called digitizer). According to this method, an original is placed upon a digitizer and then a desired image area is pressed so that it is automatically detected. This method is advantageous in that the above-described step for measuring the X and Y coordinates of a desired image area can be eliminated.
When the above-described multiple copying function, the color copying function and the function for designating a desired image area are combined, a multifunctional copying apparatus is obtained. In case of the multiple copying operation, the desired image areas to be copied are different from one original to another so that the originals must be so selected that no desired image areas are overlapped with each other. However, when the function for designating a desired image area is added, the image areas which overlap each other can be eliminated or erased so that only the desired image areas can be reproduced and consequently it is not needed to select the original. It follows therefore that by the combination of the above-described three functions, a copy sheet bearing color multi-image can be obtained from any originals.
So far the trend of the recently developed multifunctional copying apparatus has been described, but even the copying apparatus having the above-described three functions is not satisfactory in practice because of the reasons described below.
When the conventional copying apparatus is used in conjunction with a digitizer, the latter must be disposed independently of the main body of the copying apparatus and the digitizer and the main body of the copying apparatus are electrically interconnected to each other through two signal transmission cables. In case of designating a desired image area, an original is placed on the digitizer and is pressed by an input pen or the like to detect the position of the desired image area. Therefore, the digitizer which has a size greater than a predetermined size (the maximum size of an original which can be copied by the corresponding copying apparatus) must be used so that it is difficult to combine the copying apparatus with the digitizer into a unitary construction. As a result, when it is desired to designate an image area to be copied, an operator must move between the digitizer and the copying apparatus so that the copying operation becomes very cumbersome. In addition, when the operator fails to accurately designate a desired image area, the copying operation step is increased, resulting in further complicated operation. Furthermore, since the digitizer must be installed independently of the copying apparatus, the copying system becomes very expensive.